am having wetting issues with two Burr Brown Op amps. Both are SOICs with NiPdAu lead frame finishes. I have attached a photo that shows a black streak the length of the lead (before soldering). This appearance is consistent of all leads and is exist on both part numbers. I get wetting action up to that black regions but it stops at that point. Is this black demarcation common in NiPdAu lead frame finishes? Or, is this some type of oxidation of the nickel layer? I would appreciate any help with this! Thanks!